Abstract
BackgroundSeed flooding stress is one of the threatening environmental stressors that adversely limits soybean at the germination stage across the globe. The knowledge on the genetic basis underlying seed-flooding tolerance is limited. Therefore, we performed a genome-wide association study (GWAS) using 34,718 single nucleotide polymorphism (SNPs) in a panel of 243 worldwide soybean collections to identify genetic loci linked to soybean seed flooding tolerance at the germination stage.ResultsIn the present study, GWAS was performed with two contrasting models, Mixed Linear Model (MLM) and Multi-Locus Random-SNP-Effect Mixed Linear Model (mrMLM) to identify significant SNPs associated with electrical conductivity (EC), germination rate (GR), shoot length (ShL), and root length (RL) traits at germination stage in soybean. With MLM, a total of 20, 40, 4, and 9 SNPs associated with EC, GR, ShL and RL, respectively, whereas in the same order mrMLM detected 27, 17, 13, and 18 SNPs. Among these SNPs, two major SNPs, Gm_08_11971416, and Gm_08_46239716 were found to be consistently connected with seed-flooding tolerance related traits, namely EC and GR across two environments. We also detected two SNPs, Gm_05_1000479 and Gm_01_53535790 linked to ShL and RL, respectively. Based on Gene Ontology enrichment analysis, gene functional annotations, and protein-protein interaction network analysis, we predicted eight candidate genes and three hub genes within the regions of the four SNPs with Cis-elements in promoter regions which may be involved in seed-flooding tolerance in soybeans and these warrant further screening and functional validation.ConclusionsOur findings demonstrate that GWAS based on high-density SNP markers is an efficient approach to dissect the genetic basis of complex traits and identify candidate genes in soybean. The trait associated SNPs could be used for genetic improvement in soybean breeding programs. The candidate genes could help researchers better understand the molecular mechanisms underlying seed-flooding stress tolerance in soybean.
Highlights
Seed flooding stress is one of the threatening environmental stressors that adversely limits soybean at the germination stage across the globe
Phenotypic variation and correlation among seed flooding tolerance parameters To evaluate the phenotypic variation under seed flooding stress in the 243 soybean plant introductions (PIs) accessions, the seeds were treated for 72 h under flooding stress and well-watered control
Four traits viz., electrical conductivity (EC), germination rate (GR), shoot length (ShL), and root length (RL) linked to seed flooding tolerance were measured at the germination stag
Summary
Seed flooding stress is one of the threatening environmental stressors that adversely limits soybean at the germination stage across the globe. The knowledge on the genetic basis underlying seed-flooding tolerance is limited. We performed a genome-wide association study (GWAS) using 34,718 single nucleotide polymorphism (SNPs) in a panel of 243 worldwide soybean collections to identify genetic loci linked to soybean seed flooding tolerance at the germination stage. Sustainable soybean production is threatened by various abiotic stresses, including flooding. Effect of flooding on soybean includes foliar chlorosis, necrosis, stunted growth, defoliation, reduction in nitrogen fixation and plant death [7,8,9]. Plants undergo different mechanisms, including morphological, physiological, and biochemical adaptations under flooding stress at germination and seedling stages [10, 11]. Comprehending the variation in flood tolerance among the genotypes and their underlying genetic architecture is important to develop an effective breeding strategy
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